1. Field of the Invention
The present invention generally relates to biometrics.
2. Background Art
A variety of well known techniques exist for sensing, measuring, and identifying biometric characteristics. These techniques focus on unique characteristics associated with structures that form the biometrics, and which can therefore uniquely identify an individual. By way of one example, fingerprints, defined by ridges and valleys in a finger, are one such biometric.
Similarly, a variety of techniques exist for sensing and measuring physiological functions. For example, a pulse rate, defined as the number of beats-per-minute of the heart, is a measurable physiological function.
Typically, the sensors used to measure biometric information are different in structure and function from those used to measure physiological activities. For example, the optical imaging, capacitative, and piezoelectric devices typically used to detect fingerprints are quite different in structure, design and operation from the plethysmographic or infrared devices used to measure a pulse.
In some instances, however, it may be convenient or useful to obtain both biometric information and physiological activity data via a single sensor. For example, in a fingerprint sensor, it may be useful both to form an image of a fingerprint, and also to determine that the fingerprint is actually from a live finger. Therefore, combining both fingerprint detection and pulse detection in a single device may be of practical benefit for security purposes.
In other cases, such a combination may prove convenient. For example, a person carrying a personal digital support device, a medical device, or a communication device may wish to identify themselves to the device via biometric identification. At other times, the same person may also wish to use the device to monitor a physiological parameter such as pulse, for example for medical monitoring purposes.
What is needed, therefore, are systems and methods that enable pulse detection in devices conventionally configured for fingerprint detection.